Method of making sheets



Nov. 239, i925.

@FFENCE.

QTEQ QTEE, T5 TAEENTUM, PENNSYLVANEA, ASSIGNOR, BY MESNE ASSIGNMENEtS,

1'0 ALLEGHENY STEEL GQMPANY, OE BBACKENBIDGE, PENNSYLVANIA, A @QIEBQ-RATIQN 01" PENNSYLVANIA.

METHOD OF MAKING SHEETS Ito IBrawin g.

. This invention relates to the manufacture of high grade steel or alloysheets and one of the objects of'this invention is to provide a methodby means of which sheets suitable 5 for deep stamping operations andhaving a high surface finish free from scale can be readily and cheaplymanufactured.

The method is applicable to the manufacture of high grade sheets of lowcarbon steel and is particularly applicable to the manufacture of highgrade sheets from alloys in which it is difficult to remove the scaleformed during hot rolling and during an nealing at high temperatures. IThe alloys in the working of which the method of this invention isparticularly valuable are those commonly known to-day as stainless ironalloys. .llhese are made from various compositions of iron and chromiumand have a relatively low carbon content and in some cases containsilicon and other metalloids.

The chromium content generally varies from 8% to 60% with the carboncontent as low as practicable, generally ranging from 02% to 14%.

In carrying out this invention, any of the standard sheet mill methodsmay be utilized and my invention primarily consists in preventing theformation of scale durin rolling and during annealing by provi ing aprotective metallic envelope for what may be termed the stock which mayeither be the sheet bars or the rough-downs. This protective envelope,after the sheets have been finished to gauge and annealed is removed.

The rotective envelope may, and preferably oes consist of a coat ofnickel electrolytically deposited.

If the protective envelope is to be applied to the sheet bars, thebarsare first thoroughly pickled to remove the scale (in some cases,'thebars may be ground to remove the scale) and are then given a relativelythick coat of nickel by means of any of the wellknown electrolyticprocesses. The plated sheet/bars can be converted into sheets by any ofthe standard sheet mill methodsand, after the finished sheets areannealed at tem- Application filed November 10, 19%. Serial No. 749,030.

peratures sufficiently high to render them soft enough for deep stampingoperations, the protective envelope is removed. If nickel is theenvelope then the sheets are treated with any suitable nickel stripperamong those now on the mafket. If a protective coat other than nickel isused a stripper must be used (forremoving such coat from the finishedsheets) that is capable of stripping such metal without harming thesurface of the sheets therebeneath.

I have found that if sheet bars produced from ingots of iron chromiumalloys relatively low in carbon and in which the chromium content isbetween 11% and2l% are thoroughly pickled to remove the scale, are thenplated with a relatively heavy plate of nickel I can produce from suchplated bars sheets that are suitable for deep stamping operations, thathave a high surface finish and that areextremely resistant to corrosion.If it is desired to plate the rough-downs instead of the sheet bars, therough-downs must first be thoroughly pickled before plating.

The nickel protective coat, during the manufacture of the sheets, eitherfrom the plated sheet bars or from the plated roughdowns, of coursedecreases in thickness as the gauge is lessened, but always preservesthe alloy or steel underneath and, serving as a nickel envelope,prevents the sheets from scaling during hot rolling and also duringannealing at high temperatures.

After the sheets have beenstripped of the protective envelope, they maybe treated in any manner desired, either by light cold rolling orby'bufiing or polishing. The sheets, however, when the nickel coat isremoved,

can be given a fine lustrous surface by bufchromium content is in excessof 8%, which consists in forming sheet bars from such 21- 10y, inroughing down said bars, in pickling the rough-downs to remove thescale, in plating the pickled rough-downs with a protecin annealing thesame, in dissolving oil the plating and then in bufling the sheets.

In testimony whereof, I have hereunto 10 subscribed my name this 8th dayof November, 1924.

OTHO M. OTTE. v

